Tobramycin
Tobramycin sulfate
Also known as: TOBI · Brulamycin · Gernebcin · Mytobrin · Tobrex · tobramycin sulphate · Tobramycinum
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| General susceptible infections | 2 mg/kg | IV, IM, SC | q8h | — | 🌎 NA |
| Susceptible UTI | 1-2 mg/kg | SC | q8h | — | 🌎 NA |
| Sepsis | 2-4 mg/kg | IV | q8h | — | 🌎 NA |
| Soft tissue, systemic infections | 1-1.7 mg/kg IV q8h or 3-5.1 mg/kg IV q24h | IV | q8h or q24h | < 7 days | 🌎 NA |
| Systemic infections | 2 mg/kg SC q8-12h or 4-6 mg/kg SC q24h | SC | q8-12h or q24h | < 7 days | 🌎 NA |
| Persistent bacteremia | 3-5 mg/kg IV, IM, SC q8h or 9-15 mg/kg IV, IM or SC q24h | IV, IM, SC | q8h or q24h | <= 7 days | 🌎 NA |
| Gram-negative infections | 4-6 mg/kg | IV/IM/SC | q24h | Assess according to clinical response | 🌍 EU |
- General susceptible infections: Avoid use or reduce dosage in patients with renal failure; recommend therapeutic drug monitoring, particularly in young animals. Consider consolidating to once-daily dosing (e.g., 6 mg/kg q24h).
- Gram-negative infections: For severe infections (including sepsis), doses as high as 12 mg/kg/day have been advocated, but should be used with caution given potential adverse effects.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| General susceptible infections | 2 mg/kg | IV, IM, SC | q8h | — | 🌎 NA |
| Susceptible UTI | 1-2 mg/kg | SC | q8h | — | 🌎 NA |
| Sepsis | 2-4 mg/kg | IV | q8h | — | 🌎 NA |
| Soft tissue, systemic infections | 2 mg/kg IV, IM or SC q12h or 4 mg/kg IV, IM, SC q24h | IV, IM, SC | q12h or q24h | <= 5 days | 🌎 NA |
| Persistent bacteremia | 2 mg/kg IV, IM, SC q8h or 6 mg/kg IV, IM or SC q24h | IV, IM, SC | q8h or q24h | <= 5 days | 🌎 NA |
| Gram-negative infections | 4-6 mg/kg | IV/IM/SC | q24h | Assess according to clinical response | 🌍 EU |
- General susceptible infections: Consider consolidating to once-daily dosing.
- Gram-negative infections: Cats may be more sensitive to toxicity. For severe infections (including sepsis), doses as high as 12 mg/kg/day have been advocated, but should be used with caution.
Small Mammals
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections (Llamas) | 4 mg/kg IV q24h; 0.75 mg/kg IV q8h | IV | q8h or q24h | — | 🌎 NA |
- Susceptible infections (Llamas): Dosing specifically for Llamas.
Birds
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 5 mg/kg | IM | q12h | — | 🌎 NA |
| Susceptible infections | 2.5-5 mg/kg/day | Parenteral | Daily | — | 🌎 NA |
Reptiles
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 2.5 mg/kg | IM | q24h | — | 🌎 NA |
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Susceptible infections | 4 mg/kg | IV | q24h | — | 🌎 NA |
- Susceptible infections: Allows achievement of Cmax/MIC ratio higher than 10 for pathogen strains with a MIC of 1 microgram/mL.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Tobramycin is a potent parenteral aminoglycoside antibiotic primarily utilized for its excellent efficacy against severe gram-negative aerobic bacterial infections.
Key Clinical Features:
- Spectrum of Activity: Highly effective against aerobic gram-negative bacilli (e.g., Pseudomonas aeruginosa, E. coli, Klebsiella, Proteus) and some aerobic gram-positive bacteria (e.g., Staphylococcus). It is inactive against anaerobes and fungi.
- Clinical Utility: Due to its inherent toxicity profile, systemic use is typically reserved for serious, life-threatening infections where other less toxic antimicrobials are ineffective, or when treating known gentamicin-resistant strains.
- Toxicity Profile: Like all aminoglycosides, it carries significant risks of nephrotoxicity and ototoxicity. Some laboratory evidence suggests it may be slightly less nephrotoxic than gentamicin, though this remains clinically debated.
Clinical Pearl: Aminoglycosides exhibit concentration-dependent bactericidal activity and a significant post-antibiotic effect (PAE). This pharmacokinetic/pharmacodynamic profile strongly supports the modern practice of high-dose, extended-interval (once-daily) dosing. This approach maximizes the $C_{max}$/MIC ratio for bacterial killing while providing a drug-free interval that allows renal tubular cells to clear the drug, thereby minimizing nephrotoxicity.
Mechanism of action
Tobramycin is a bactericidal antibiotic that disrupts bacterial protein synthesis.
- Cellular Entry: The drug enters the bacterial cell via an oxygen-dependent active transport mechanism.
Note: Because this transport requires oxygen, aminoglycosides are completely ineffective against obligate anaerobic bacteria and have reduced efficacy in anaerobic environments (e.g., abscesses, necrotic tissue).
- Target Binding: Once inside, tobramycin irreversibly binds to the 30S ribosomal subunit.
- Mechanism: Binding → misreading of mRNA → incorporation of incorrect amino acids into the growing peptide chain → production of non-functional or toxic proteins → bacterial cell death.
- Environmental Factors: Antimicrobial activity is significantly enhanced in an alkaline environment and diminished in acidic, purulent conditions.
Safety & warnings
Contraindications
- Known hypersensitivity to aminoglycosides
- Rabbits and hares (causes fatal disruption of GI flora)
- Pre-existing severe renal disease (unless benefits outweigh risks)
- Dehydration
- Corneal ulceration (specifically for ophthalmic preparations)
Adverse effects
- Nephrotoxicity (acute tubular necrosis)
- Ototoxicity (vestibular and auditory damage, potentially irreversible)
- Facial edema
- Pain or inflammation at the injection site
- Peripheral neuropathy
- Hypersensitivity reactions
- Rarely: GI signs, hematologic, and hepatic effects
- Neuromuscular blockade (rare)
Precautions
Extreme Caution Required:
- Renal Impairment: Use with extreme caution in patients with preexisting renal disease. Dosage intervals must be extended, and therapeutic drug monitoring is highly recommended.
- Risk Factors: Neonatal and geriatric patients, fever, sepsis, and dehydration significantly increase the risk of toxicity.
- Working Dogs: Use cautiously in working dogs (e.g., seeing-eye, herding, hearing-assistance dogs) due to the risk of irreversible ototoxicity (deafness or vestibular dysfunction).
- Neuromuscular Disorders: Avoid or use with extreme caution in patients with myasthenia gravis or other neuromuscular disorders due to the drug's neuromuscular blocking activity.
- Feline Sensitivity: Cats appear to be particularly sensitive to the vestibular toxic effects of aminoglycosides.
Drug interactions
Synergistic antibacterial effects in vivo; however, can cause physical inactivation of aminoglycosides if mixed in the same syringe or IV line, or in vivo in patients with severe renal failure.
Potential for additive nephrotoxicity (historically documented with older generation cephalosporins like cephalothin).
Increased risk of nephrotoxicity and ototoxicity.
Increased risk of nephrotoxicity and ototoxicity.
Significantly increased risk of acute kidney injury.
Concomitant use can potentiate and prolong neuromuscular blockade, potentially leading to respiratory paralysis.
Increased risk of nephrotoxicity
Increased risk of ototoxicity and nephrotoxicity
In vitro chemical inactivation if mixed
Enhanced non-depolarizing neuromuscular blockade
Monitoring
- Clinical efficacy (resolution of fever, improved clinical signs, negative follow-up cultures)
- Renal toxicity: Baseline and serial urinalysis (monitoring for tubular casts, which are often the first sign of impending toxicity), urine specific gravity, serum creatinine, and BUN
- Gross monitoring for vestibular toxicity (head tilt, nystagmus, ataxia) or auditory toxicity (deafness)
- Therapeutic drug monitoring (peak and trough serum levels) is highly recommended to ensure efficacy and prevent toxicity
- Urinalysis (daily, looking for cellular casts as an early warning)
- Serum creatinine and BUN (baseline and periodically)
- Hydration status and urine output
- Auditory and vestibular function
Pharmacokinetics
Half-life
Absorption
Not appreciably absorbed after oral or intrauterine administration. Absorbed from topical administration during surgical irrigations. Bioavailability from extravascular injection (IM or SC) is >90%. SC injection results in slightly delayed peak levels compared to IM.
Distribution
Distributed primarily in the extracellular fluid. Found in ascitic, pleural, pericardial, peritoneal, synovial, and abscess fluids. High levels in sputum, bronchial secretions, and bile. Minimally protein bound (<20%). Does not readily cross the blood-brain barrier or penetrate ocular tissue. Crosses the placenta (fetal concentrations 15-50% of maternal serum). Accumulates in inner ear and kidneys. Volume of distribution (horses): 0.24-0.55 L/kg.
Metabolism
Aminoglycosides are not significantly metabolized.
Elimination
Eliminated almost entirely by glomerular filtration. Clearance (horses): 101-130 mL/kg/hr. Patients with decreased renal function can have significantly prolonged half-lives.
Overdose
In the event of an inadvertent overdose, rapid intervention is required to prevent permanent renal and otic damage:
- Hemodialysis: Highly effective in reducing serum levels of the drug, though rarely available in veterinary practice.
- Peritoneal Dialysis: Can reduce serum levels but is significantly less efficacious than hemodialysis.
- Drug Complexation: Intravenous administration of carbenicillin or ticarcillin (12-20 grams/day in humans) can complex with tobramycin in the blood, inactivating it. This is reportedly nearly as effective as hemodialysis.
Available products
Formulations
- Injection solution
- Powder for injection
- Inhalation solution
- Ophthalmic preparations
- Injectable: 40 mg/ml solution
Veterinary
- Tobramycin 40 mg/ml injectable solution
Human-labeled
- Tobramycin Sulfate Injection: 0.8 mg/mL and 1.2 mg/mL in single-dose containers
- Tobramycin Sulfate Solution for Injection: 10 mg/mL and 40 mg/mL
- Tobramycin Sulfate Powder for Injection: 1.2 grams (40 mg/mL after reconstitution)
- Tobramycin Solution for inhalation: 60 mg/mL (TOBI)
- Nebcin 40 mg/ml injectable solution
Regulatory status
POM (Prescription Only Medicine)
POM-V
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store at room temperature (15-30°C); avoid freezing and temperatures above 40°C. Do not use the product if discolored.
Client information
Tobramycin is a powerful antibiotic reserved for serious infections. Because of its strength, it requires careful monitoring to ensure your pet's safety.
- Administration: If you are instructed to give subcutaneous (under the skin) injections at home, ensure you understand the exact technique and dosing schedule. Never give more than prescribed.
- Potential Risks: This medication carries a risk of causing kidney damage and hearing or balance problems (ototoxicity).
- What to Watch For: Contact your veterinarian immediately if you notice any of the following:
- Changes in urination (drinking more, urinating more, or urinating less)
- Loss of balance, stumbling, head tilt, or abnormal eye movements
- Apparent hearing loss or unresponsiveness to sounds
- Lethargy, vomiting, or loss of appetite
- Follow-up: Keep all appointments for blood and urine tests. These tests are crucial to catch early signs of kidney stress before permanent damage occurs.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.